ActionMCP is a Ruby gem that simplifies the integration of Ruby and Rails applications with the Model Context Protocol (MCP) standard. It offers base classes and helpers for creating MCP applications, allowing developers to focus on application logic while handling the boilerplate for MCP compliance. With ActionMCP, Rails applications can expose prompts, tools, and resource templates to large language models (LLMs) through a network-based deployment, making it easier to connect AI assistants to external data sources and tools.